A human culture with origins stemming from Native American Indians, captured by the Goa'uld and deposited on PXY-887 millennia ago. The Salish were aided by Xe'ls, a member of an alien species who fought the Goa'uld until their forces were driven away. These beings chose to remain, co-existing with the Salish in the forms of their "Spirits" to protect them.
Like many Native American tribes, the Salish are one with their environment and see all mechanical disruption in their world (such as mining) to be a malicious act of violence and a rape to the natural environment. Their world is rich in the mineral trinium, the first the S.G.C. discovered. They receive all of their needs of the ore, as they say, by asking the mountain to send the "key" down the river, where it is purified by the water over an extended period of time.
The Salish possess the means to develop rudimentary technologies, such as bows and arrows, and commonly use trinium spears and darts. They are effective at tranquilizing intruders for several hours, as well as breaking bullet-proof glass.
Thanks to SG-1, the Salish Spirits, now on Earth, were unable to maintain their identity, and asked the Indians what form they wished the spirits to exist in. The humanoid form of the spirits pleased them greatly, and they returned to their original planet to co-exist with them in a truer form.
Spirits - SG-1 encounters the Salish after failed attempts to mine their world of trinium, and fails at negotiations to gain the ore by any means other than what the mountain can provide.